Comparison of the Protective Effect of Isoproterenol with Isoproterenol-Phenylephrine Aerosols in Asthmatics

Abstract

The protective effect of isoproterenol and phenylephrine aerosol (Medihaler-Duo) against histamine-induced asthma and dyspnea on exertion is increased considerably and is of significantly longer duration than that of isoproterenol alone (Medihaler-Iso). The initial effects of both preparations are equally good, but the increased vital capacity obtained with the use of isoproterenol plus phenylephrine is maintained more than twice as long as that obtained with isoproterenol alone in the quantities delivered by each of these aerosol products. The protective effect against dyspnea on exertion in asthmatic patients is maintained for 30 minutes by isoproterenol alone and for more than 120 minutes by isoproterenol plus phenylephrine. No side effects were noted.